Elongate medical device

ABSTRACT

This invention relates to an elongate medical device, with a distal end to be advanced into the body of a patient and then withdrawn from the body and an elongate shaft connecting the distal end with a proximal end that remains outside the body, the shaft extending in use through a hole in the skin of the body characterized by a slider, captivated on a portion of the length of the shaft, which is capable of lining the said hole, as the shaft is advanced and withdrawn relative to said hole and the slider in the hole, said slider having a maximum outer diameter that is substantially the same as or Jess than a maximum outer diameter of the distal end.

PRIORITY

This application is a continuation of U.S. application Ser. No.12/742,655, filed Aug. 23, 2010, now U.S. Pat. No. 9,186,482, which is aU.S. national stage application under 35 USC §371 of InternationalApplication No. PCT/EP2008/065385, filed Nov. 12, 2008, claimingpriority to United Kingdom Application No. 0722192.2, filed Nov. 12,2007, each of which is incorporated by reference in its entirety intothis application.

TECHNICAL FIELD

This invention relates to an elongate medical device, with a distal endto be advanced into the body of a patient and then withdrawn from thebody, and an elongate shaft connecting the distal end with a proximalend that remains outside the body, the shaft extending in use through ahole in the skin of the body.

BACKGROUND PRIOR ART

A catheter serving as a stent delivery system is just one example of amedical device with a distal end that is advanced into the body througha percutaneous puncture. The distal end advances in the bodytransluminally. Often, the lumen is part of the cardiovascular system,but not necessarily. In one very common procedure, known as theSeldinger technique, catheters are introduced into the cardiovascularsystem through a puncture point in the thigh of the patient.

As stent delivery catheter devices become more sophisticated, they havebecome more compact, in cross-sectional areas. The normal unit ofdimension to designate cross-sectional areas is the unit of lengthcalled “French” which is ⅓ of a millimeter. Thus, a “Six-French”catheter has an outside diameter of two millimeters.

With increasing diameter, the demands on tissue at the point of entry tothe body, and the risk of leakage of blood at that entry point, tend toincrease. Typically, a catheter is introduced at the point of entry ofthe body through an introducer sleeve which extends from outside thebody, through the puncture point, into the lumen of interest, to providea path along which the distal end of the catheter can advance throughthe percutaneous puncture and into the desired lumen. However, theprovision of such an introducer sleeve increases the diameter required,at the point of entry to the body. Self-evidently, doing without anyintroducer sleeve would be one way to reduce the total diameter needed,at the point of entry. Indeed, some doctors are responding to tissuedifficulties at the point of entry by performing the catheterintroduction without any introducer sleeve. While this reduces the totaldiameter requirement, it brings disadvantages, specifically, that theabluminal surface of the catheter moves longitudinally, proximally anddistally, against the bodily tissue at the point of entry, tending toincrease the likelihood of loss of blood at that entry point.

An elongate medical device that is advanced transluminally within thebody of a patient usually has a distal end that is to perform some sortof medically advantageous function within the body, such as deploying astent. Normally, the shaft serves as a link between the proximal anddistal ends of the device but does not have to perform a medicalprocedure in its own right, so it can be slimmer. The present inventionis particularly adapted to medical devices in which the maximumcross-section of the distal end of the device is greater than themaximum cross-sectional area of the shaft portion. For examples ofmedical devices featuring a distal tip that is somewhat thicker than itsshaft, reference is made to EP-A-1025813 and U.S. Pat. No. 5,772,669.

In order to reduce the leakage of blood through the entry point, oftenreferred to as “backbleed”, the use of an additional sleeve placedaround the catheter shaft has been suggested in U.S. Pat. No. 5,203,774.This sleeve is slidably arranged on the catheter shaft so that it can beaxially displaced with respect to the catheter and has a distal end forbeing introduced into the inner lumen of an introducer sleeve. A flangewith a diameter that is larger than that of said distal end is providedat a proximal end of the sleeve. The flange engages over the edges ofthe introducer sleeve so as to prevent the sleeve from being axiallydisplaced. Such an arrangement allows the catheter shaft to be freelyadvanced and retracted with respect to the sleeve partly positioned inthe introducer sleeve but reduces backbleed that, in the absence of thesleeve, may occur through the gap between the inner lumen of theintroducer sleeve and the catheter shaft. A similar sleeve configurationis also disclosed in U.S. Pat No. 5,836,306 and U.S. Pat. No. 5,334,160.

The sleeve arrangements described in the above-referenced documentsought to reduce the occurrence of backbleed, in particular with respectto the length of constant external diameter of the shaft of the catheteras it is introduced into a patient's body. These sleeves are configuredto be disposed within a proximal portion of an introducer sleeve andprevented from any further distal movement in an axial direction of thecatheter shaft by a proximal sleeve portion, such as a flange, that hasan outer diameter larger than the inner diameter of the proximalintroducer sleeve portion. Hence, the length along which the medicaldevice can be introduced into a patient's body is limited to the lengthof the catheter shaft which can advance through the sleeve.Specifically, if the catheter were to have a thicker proximal shaftportion which has an outer diameter larger than the inner diameter ofthe sleeve, then such a proximal portion would have to remain at alltimes proximal of the backbleed-preventing introducer sleeve.

In peripheral vascular procedures, the distance between the point ofbodily entry and the site of surgical treatment within the body canwidely vary and may not be known precisely in advance of the procedure.

FR-A-2 625 897 discloses a conically shaped plug element that isslidably disposed around the tube of a medical probe. After the probehas been introduced into the blood vessel of a patient, the plug elementis arranged and fixed within the entry point of the vessel so as totightly seal it. When inserted in the entry point, the plug elementexerts a pressure on the probe tube that is sufficient to prevent itfrom moving in an axial direction of the probe. In this way, the probeis immobilized in a desired position with respect to the blood vessel.

SUMMARY OF THE INVENTION

According to the present invention there is provided an elongate medicaldevice as identified above, and characterized by a slider, captivated ona portion of the length of the shaft, which is capable of lining thesaid percutaneous hole as the shaft is advanced and withdrawn relativeto said hole and to the slider in the hole, said slider having a maximumouter diameter that is substantially the same as or less than a maximumouter diameter of the distal end of the medical device.

It will be appreciated that a medical device provided with the slider ofthe invention can function without an introducer sleeve. The distal endof the device is advanced distally through the hole that is the point ofentry into the body and then, once the distal end is through the hole,the slider can be positioned within the hole, to line the hole. Afterthat, the shaft of the medical device can be advanced distally throughthe lined hole, with relative sliding motion between the shaft portionand the luminal surface of the slider, while the abluminal surface ofthe slider remains motionless on the bodily tissue defining the holethat is the entry point in the body. It will be appreciated that thepresence of the slider in the hole is useful for restricting orinhibiting flow of blood from within the body, through the hole, tolocations outside the body.

Further, it will be appreciated that the presence of the slider in thehole can reduce the degree of trauma imposed on the tissue surroundingthe hole, not only because that tissue is no longer subject to thesliding motion over the tissue of the advancing or withdrawing shaftportion but also because the tissue need not be stretched further, inorder to incorporate an introducer sleeve that has a diameternecessarily greater than the maximum diameter of the distal end of theelongate medical device.

It will further be appreciated that medical devices in accordance withthe present invention can easily be designed in such a way as to becompatible with an introducer sleeve. This is advantageous for it givesthe decision-making medical practitioner the choice of employing anintroducer sleeve, or of choosing to do without one, without having toswitch from one elongate medical device to another.

Furthermore, the slider of the present invention has a maximum outerdiameter that is substantially the same as or less than a maximum outerdiameter of the distal end. Thus, the slider can be advanced through theentry point and beyond, into the accessed lumen of the patient's body,whether or not an introducer sleeve is used. In this way, the length ofan introduction path of the medical device is not limited by thepresence of the slider. Hence, the same device can be used for differentprocedures with varying distances from the entry point to the area to betreated within the body, which is particularly advantageous inperipheral vascular procedures as explained above.

The shaft of the medical device may have a proximal portion with adiameter that is greater than the diameter of the shaft portion otherthan the proximal portion. In particular, the proximal portion may havea maximum outer diameter that is substantially the same as or less thanthe maximum outer diameter of the distal end. In this case, dependingupon the distance between the point of entry and the point of surgicaltreatment, he proximal shaft portion can be proximal of the entry pointinto a patient's body (with the sleeve lining the entry point orintroducer) or bridging the entry point (in which case the sleeve iswholly distal of the entry point and any introducer element throughwhich the medical device extends at the point of entry)

Of particular interest for releasing self-expanding stents are cathetersthat include a pull wire, in a lumen in the shaft of the catheter thatis pulled proximally progressively to release the stent from within aconfining sheath, starting at the distal end of the stent. During suchrelease, the wire moves proximally through the catheter introducerlumen, but not the abluminal surface of the stent delivery catheter.

One preferred embodiment of a slider has an outside diameter not greaterthan the maximum diameter of the distal end of the elongate medicaldevice, yet larger than the outside diameter of a shaft portion on whichthe slider is slidable. We think that a slider length in a range of from1 mm to 4 mm will be attractive to medical practitioners and, currently,a slider length of around 15 mm is thought to be particularly suitable.Most of the axial length of the slider, in preferred embodiments, willhave a circular cross-section cylindrical abluminal surface, flanked ata proximal and distal end by tapered portions, tapering inwardly inorder to minimize tissue trauma when the slider is brought intocoincidence with the entry point hole in bodily tissue.

The reader will appreciate that the slider should slide freely on theshaft portion and that this process might be assisted by providing theluminal surface (bore surface) of the slider with a lubricious coating.As to the abluminal surface of the slider, skilled readers will havecommon general knowledge what sorts of surfaces are best adapted forresiding in entry point punctures. Those engineers responsible, forexample, for designing and constructing introducer sleeves will haveconsiderable experience what sorts of surfaces to adopt. One imagines arange of coatings might be useful for the abluminal surface of theslider, even perhaps including a blood clotting agent, further to reduceflow of blood over the slider surface, outwardly of the body.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a medical device.

FIG. 2 is a section view along the longitudinal axis of a medicaldevice.

FIG. 3 is a section view along the longitudinal axis of another medicaldevice.

DESCRIPTION

For a better understanding of the present invention, and to show moreclearly how the same may be carried into effect, reference will now bemade, by way of example, to the attached drawings, in which FIG. 1 is areproduction of FIG. 1 of EP-A-125813, modified to show a slidercaptivated on a shaft portion of the stent introducer catheter showed inthe drawing, and FIGS. 2 and 3 show a stent introducer catheter such asthat of FIG. 1 that is inserted into a patient's body.

The drawing is a simplified perspective view of a stent deliveryapparatus 1 which comprises inner and outer coaxial tubes. The innercatheter 12 extends along the length of an outer shaft portion 40, froma proximal end 42 to a distal end 45. The distal end 45 of the shaft 40includes an enlarged section 44 that has a larger outside diameter thanthe outside diameter of the shaft 40. Enlarged section 44 houses (notshown) a stent 50 that is to be delivered by the device. The device isan over-the-wire device that advances along a guidewire 76.

Mounted on the shaft 40 is a slider 60, to be a relatively tight slidingfit on the outside surface of the shaft 40. It has a length of 15 mm andis basically an annulus 62 of circular cross-section cylindrical formwith a diameter of typically 7 French and the ends 64, 66 of thecylinder are tapered for reduction of the amount of trauma caused totissue if the slider is advanced through the percutaneous entry pointfor the stent delivery catheter system into the body.

In the illustrated embodiment, the shaft portion on which the slider mayslide is a portion running the full length of the shaft, from the distalend 45 to a proximal hub 52. In other embodiments, however, such as thatshown in FIGS. 2 and 3, the shaft portion on which the slider slidesmight constitute only a relatively small portion of the total length ofthe medical device, for example, corresponding to that part of thelength of the shaft which will reside in the entry point hole while themedical device is actually performing a medical procedure within thebody.

While the illustrated embodiment has a smooth constant diametercylindrical abluminal surface, other embodiments of slider might haveother abluminal surface topographies including, for example, axialridges or grooves, perhaps to retain desired fluid coating materials, ortransverse ridges or grooves, perhaps to further limit passage of bloodbetween the slider and the surrounding bodily tissue. Similarly, on theluminal surface of the slider, one can envisage whatever topography bestachieves the sliding sealing effect desired. In any event, it isexpected that the medical practitioner will need manually to manipulatethe slider into exactly that location within the entry point hole thatthe doctor thinks is optimal. For that, the abluminal surface of theslider, accessible from the proximal end of the slider, would need to becompatible with some sort of grip imposed on the slider by the medicalpractitioner. However, if the medical device is to be compatible withuse through an introducer sleeve, then whatever means are provided atthe proximal end of the slider to facilitate gripping by the doctor 1;this should not conflict with passage of the slider through theintroducer sleeve, both distally and proximally. In particular, the needto withdraw the slider proximally through the introducer sleeve, from aposition where it is entirely distally beyond the distal-most point ofthe introducer sleeve, as shown in FIG. 2, ought not to be overlooked.One envisages that the distal end of the introducer sleeve would abutthe proximal end of the slider while the shaft of the medical device isbeing withdrawn proximally through the introducer sleeve, and only whenthe distal end of the slider is butted up against the larger diameterdistal end portion of the elongate device would the inwardly taperedproximal end of the slider advance proximally into the interior of theintroducer sleeve.

FIGS. 2 and 3 show cross-sectional views of a part of a stent introducercatheter 100 that has been introduced into the lumen of a blood vessel30 through an entry point hole 70 in the body of a patient with the helpof an introducer sleeve 80. The configuration of the proximal part ofthe stent introducer catheter 100, which is not shown in FIGS. 2 and 3,is comparable to that of the stent introducer catheter 1 shown in FIG. 1and skilled readers are in any case familiar with the details ofconstruction and operation of the actuator devices that are located atthe proximal end of a stent delivery catheter. Furthermore, the samereference signs as in FIG. 1 will be used for identical and equivalentelements.

The stent introducer catheter 100 has a disal end 45 with a maximumouter diameter Dd that houses a self-expanding stent 50. The distal end45 is connected with a proximal end (not shown) of the device by a shaftportion 40 having a proximal portion 42 with a larger diameter Dp and adistal portion 46 with a smaller diameter. A slider 60 with an outerdiameter Ds that has substantially the same configuration as that shownin FIG. 1 is slidably disposed around the distal shaft portion 46 sothat it can freely move in an axial direction between the proximal shaftportion 42 and the distal end 45 of the catheter 100. The outerdiameters of the proximal shaft portion 42, the slider 60 and the distalend 45, Dp, Ds and Dd are substantially identical.

The stent introducer catheter 100 further comprises a pusher element 72that is disposed within an inner lumen of the shaft portion 40. Thepusher element 72 has a distal end 74 that abuts the proximal end of thestent 50 during stent deployment thus holding he stent in its axialposition. The distal shaft portion 46 is at its proximal end 47connected to a pull wire 48 that runs inside the proximal shaft portion42 all the way to the proximal end (not shown) of the stent introducercatheter 100.

FIGS. 2 and 3 both show a configuration, after advance of the stent tothe site of stenting but prior to deployment of the stent, in which thestent introducer catheter 100 has already been introduced into apatient's blood vessel 30 such that its distal end 45 is positioned at astenosis 90. In the case of FIG. 2, the stenosis 90 is spaced from theentry point hole 70 by a distance close to the full length of thecatheter shaft. Otherwise, in the case of FIG. 3, the stenosis 90 liescloser to the entry point hole 70. Since the outer diameters Dp, Ds andDd of the proximal shaft portion 42, the slider 60 and the distal end 45are all substantially identical and all a snug fit with the bore of theintroducer sleeve 80, the stent introducer catheter 100 can be used,substantially free of backbleeding, for both cases without therequirement of any modifications to the device 100. In this way, thestent delivery system can be used, unmodified, regardless how near orfar the stenosis is from the point of percutaneous entry of the catheterinto the bodily lumen.

Next, the operation of the stent introducer catheter 100 for deployingthe stent 50 is described. When the distal end 45 is arranged in theblood vessel 30 in such a way that the stent 50 is in a desired positionat the site of the stenosis 90, as shown in FIGS. 2 and 3, the medicalpractitioner causes the pull wire 48 to be pulled proximally at theproximal end of the stent introducer catheter 100. This pulling forcecauses a proximal movement of the distal shaft portion 46 andconsequently also the enlarged section 44 relative to the pusher element72 which is free from axial translation of movement during thedeployment procedure. Since the stent 50 is securely held in itsposition by abutment on the distal end 74 of the pusher element 72, theenlarged section 44, which is an outer sheath holding the stent 50 inits compressed state, is retracted from the abluminal surface of thestent 50, allowing the stent 50 to radially expand. Once the stent 50 isfully deployed, the stent introducer catheter 100 can be removed fromthe patient's body through the introducer sleeve 80.

In the case shown in FIG. 2, the proximal shaft portion 42, which isstationary during stent deployment, is positioned within the introducersleeve 80, while in the case shown in FIG. 3 the slider 60 is arrangedin this position. Importantly, in both cases, there is no contactbetween the inner surface of the introducer sleeve 80 and any movingpart of the stent introducer catheter 100, such as the distal shaftportion 46, thereby greatly reducing friction during the stentdeployment process. The inventor has found out that such friction canlead to serious complications during the medical procedure. Inparticular, if the distal shaft portion 46, because of contact with theinner surface of the introducer sleeve 80, is prevented by frictionbetween the shaft and the introducer is prevented from sliding smoothlyproximally through the point of percutaneous entry while at the sametime a relative movement of the distal shaft portion 46 and the pusherelement 72 is effected by the medical practitioner by proximally pullingthe pull wire 48, the stent 50 can be pushed forward along the bodilylumen in an axial direction, away from its desired location. Any suchbehavior could lead to dangerous inaccuracies in the placement of thestent 50. With the stent introducer catheter 100 of the presentembodiment such complications can be reliably avoided, enabling stentdeployment with a high degree of accuracy of placement, independent onwhether the stenosis 90 to be treated is located close to or far awayfrom the entry point hole 70, and all using just one introducer catheterlong enough to reach stenting sites furthest away from the point ofentry of the delivery system.

If no introducer sleeve 80 is used and the stent introducer catheter 100is introduced directly through the entry point hole 70, theconfiguration of the present embodiment has the additional advantagethat any movement of the distal shaft portion 46 against the bodilytissue at the point of entry is avoided, thus not only any tendency tobackbleed but also reducing trauma to bodily tissue at the point ofentry.

Although the illustrated embodiments are of a stent delivery systemcatheter, an over-the-wire catheter for a self-expanding stent 1 thereader will appreciate that the slider idea of the present invention isapplicable to other sorts of catheters and indeed to medical devicesintroduced into the body that are strictly not correctly identified as acatheter. Whereas the slider invention might still be useful atdiameters of 6 French and below, it is thought that the slider ideabegins to become particularly interesting for medical practitioners, assoon as the overall diameter of the device to be introduced into thebody begins to increase substantially above 7 French.

In general, skilled readers will appreciate that the invention has wideapplication beyond the specific device shown in the drawing, and thatwide variation is possible in the features of construction and selectionof materials in the slider of the invention. Readers will bring to bareon the matter their background and experience in the field of catheterintroducer sleeves and transluminal stent delivery systems.

1. An elongate medical device comprising: an elongate shaft having ashaft distal end, a proximal end, and a cross-section, wherein the shaftdistal end includes a pull-back sheath; a stent covered by the shaftdistal end; and a slider captured on the shaft between the shaft distalend and the shaft proximal end and configured to line a percutaneoushole during a percutaneous medical procedure allowing a shaft to advanceinto and retract from the percutaneous hole, the slider having a maximumouter diameter that is substantially the same as or less than themaximum outer diameter of the shaft distal end, wherein a pull wiredisposed within the shaft attached to the pull-back sheath andproximally operable.
 2. The device of claim 15 provided that the devicedoes not have an introducer sleeve.
 3. An elongate medical devicecomprising: a sheath distal end; an elongate shaft connecting the sheathdistal end with a sheath proximal end, the shaft extendingpercutaneously in use; a stent covered by the sheath distal end; and aslider captured on the shaft between the shaft distal end and the shaftproximal end and configured to line a percutaneous hole during apercutaneous medical procedure allowing a shaft to advance into andretract from the percutaneous hole, the slider having a maximum outerdiameter that is substantially the same as or less than the maximumouter diameter of the shaft distal end, wherein the shaft has a proximalportion has a diameter that is greater than a diameter of that portionof the shaft that is between the shaft proximal portion and a shaftdistal portion and wherein the shaft proximal portion has a maximumouter diameter that is substantially the same as a maximum outerdiameter of the sheath distal end.
 4. The device of claim 3 providedthat the device does not have an introducer sleeve.
 5. The deviceaccording to claim 4 wherein the proximal portion abluminal surface doesnot move proximally during stent deployment.
 6. The device according toclaim 4 wherein the slider has a maximum outer diameter that issubstantially the same as the maximum outer diameter of the shaftproximal portion.
 7. An elongate medical device comprising: apercutaneously adapted shaft having a distal end including a pull-backsheath adapted for internal placement and a proximal end adapted toremain outside the body wherein the proximal end encloses a single lumenconnecting the shaft distal and proximal ends, a stent covered by theshaft distal end; and a slider captured on the shaft between the shaftdistal end and the shaft proximal end and configured to line apercutaneous hole during a percutaneous medical procedure allowing ashaft to advance into and retract from the percutaneous hole, the sliderhaving a maximum outer diameter that is substantially the same as orless than the maximum outer diameter of the shaft distal end, whereinthe shaft portion includes a pull wire for manipulating the pull-backsheath proximally.
 8. The device of claim 7 provided that the devicedoes not have an introducer sleeve.
 9. An elongate medical devicecomprising: a shaft distal end, an elongate shaft enclosing a singlelumen connecting the shaft distal end with a shaft proximal end, in usethe shaft extending percutaneously, a stent covered by the shaft distalend; and a slider captured on the shaft between the shaft distal end andthe shaft proximal end and configured to line a percutaneous hole duringa percutaneous medical procedure allowing a shaft to advance into andretract from the percutaneous hole, the slider having a maximum outerdiameter that is substantially the same as or less than the maximumouter diameter of the shaft distal end, wherein the shaft has a proximalportion having a diameter that is greater than a diameter a middleportion of the shaft that is distal of the shaft proximal portion andproximal of a shaft distal portion, and the shaft proximal portion has amaximum outer diameter that is substantially the same as a maximum outerdiameter of the shaft distal end.
 10. The device according to claim 9provided that the device does not have an introducer sleeve.
 11. Thedevice according to claim 10 wherein an abluminal surface of theproximal portion of the shaft does not move proximally during deploymentof the stent.
 12. The device according to claim 10 wherein the sliderhas a maximum outer diameter that is substantially the same as themaximum outer diameter of the shaft proximal portion.